1. Field of the Invention
This invention relates to a bus bar used in a circuit inside an electrical connection box, etc., of an automotive vehicle.
2. Description of the Related Art
In recent years, a bus bar has been used as a power terminal of an inverter in a hybrid car. For example, bus bar 11 shown in FIG. 3, has an essential part with a thickness t and width 2b as shown in FIG. 2B, which determines an allowable current therein. Bus bar 11 is manufactured in a predetermined shape by punching a plate into a blank with thickness t and width 2b and bending it.
Bus bar 11 includes body portion 13 which is the essential linear part, as a current conductor. Body portion 13 has wide terminal portion 15 expanded in the horizontal direction perpendicular to the longitudinal direction, in order to be connected to an electric wire, etc. One end of body portion 13 has multiple bends and formed with connection hole 17, which is connected to a terminal of a conductor by bolts, etc. Bus bar 11 is also used for connecting other types of conductors (for example, cable, wiring harness) to terminal portion 15 or connecting hole 17.
Bus bar 11 is required to have high conductivity and heat radiation efficiency which is sufficient to supply a large current. Especially, in order to improve heat radiation efficiency, the surface area per unit length is required to be increased and because of this, this requirement is conventionally carried out by increasing thickness t and width 2b. 
Therefore, there is a problem that the volume per unit length is increased, which means that a plate to be punched may become bulky, and at the same time increasing the geometrical moment of inertia, resulting in difficulty in bending and manufacturing.
This type of bus bar is disclosed in Japanese Unexamined Patent Publication No. 2002-281645.